Application Ser. No. 022,453 discloses a power supply and electronic controller-timer combination for a lighting power circuit in which the controller-timer, arranged for either automatic user-programmed or manual control of a power switch, and its power supply can be connected in series with the alternating current power source and the lighting device load. Thus, a lighting fixture, normally controlled by a single-pole wall mounted switch, is automatically or manually controlled by the electronic control system there disclosed which replaces the single-pole switch with a power switch, like a triac, connected in series with the load in the same manner as the original switch. It is obvious that for the above-mentioned system reliably to operate, the controller must be supplied with power at all times, even when the controller-timer closes the power circuit and nearly all of the source voltage is dropped across the load. In such case, the power supply preferably draws its operating power from across the triac during the few degrees at the beginning of each operation half cycle during which the triac is non-conductive before it is re-fired.
The mass customer commercial acceptance of such a controller-timer depends on the ability of almost any user to install the apparatus in place of any single-pole wall switch. Since the operation of the controller-timer depends on a continuously energized power supply, the presence of additional switches in series with the replaced wall switch, such as in a 3-way circuit, renders the controller-timer inoperative as soon as the latter switch is opened.
The controller-timer disclosed in this application is a 24-hour repeat cycle timer which preferably has a control marker storage memory unit, which is most advantageously a recirculating marker bit shift register, energized from said power supply and having the same number of stages or storage locations as the number of basic programmable time intervals, e.g. 15 or 30 minutes, over a 24-hour period. Output sensing from a selected register stage actuates the triac in a conductive or non-conductive mode in accordance with the pattern of "ON" or "OFF" marker bits stored in the memory unit. The marker bit pattern is advanced automatically at the regular basic timing intervals by internal timing means. A pushbutton control is provided both for normal non-timer operation of the triac and as an override control to allow the user to change the state of the triac while the timer is in a timer-on mode of operation without disturbing the stored bit pattern. The timer can be rapidly programmed to set the desired pattern of markers in the memory unit in a manner of a minute or so by rotating a time interval indicating dial knob which may also act as the depressible pushbutton, and depressing the same at the desired time to effect the desired triac state. In another mode of operation, real time programming is achieved during the first 24 hours after the timer is activated by application of power in accordance with the load device on and off duty profile as obtained by the normal operation of the pushbutton used as a normal on and off control.
The controller-timer just described obviously cannot, without the features of the invention to be described, be useable in series with a 3-way single pole switch not only because this switch can be operated to a circuit-opening condition which would cause the power supply to fail and the controller-timer to become inoperative with loss of the volatile marker bits stored in the memory unit, but also because of the fact that the user may mistakenly believe that a single pole switch still in series with the old replaced switch can operate the lighting circuit involved and program the timer in the same way as the pushbutton operates to carry out these functions. This problem can be overcome by the user removing this single pole switch and jumpering the power circuit connected terminals thereof. However, it is desirable to avoid the necessity of the user removing the single pole switch, and to enable the user to use this single pole switch for both programming of the timer, and for operation of the lighting circuit when the timer is on or off, so that it duplicates the operation of the controller-timer pushbutton.
It is accordingly, one of the objects of the invention to provide an electric controller including a power switch, such as a triac, to be connected in series with an external power circuit which includes a single pole switch in series with the power switch and wherein the controller may be operated and preferably also programmed by operation of the single pole switch.
A related object of the invention is to provide a controller-timer as described above, wherein the single pole switch connected in series therewith duplicates the function of the pushbutton control described, so that its successive operation energizes and de-energizes the load circuit involved and can program the timer.
A more specific object of this invention is to provide for a "3 way" (two location) switch control system in a constantly connected series circuit consisting of a source of electrical power, a single conductor connecting one polarity of the power source to a load, a single conductor connecting the load to either of the two control locations, two conductors connecting the two control locations, and a single wire connecting the second control location to the other polarity of the power source. It is a further object of this invention to permit one of the control locations to use a single pole switch to effect a change of state of the power applied to the load whenever the single pole switch is operated to one or the other of a pair of contacts, said change of state of the load condition to take place regardless of whether the single pole switch is operated from one or the other of said contacts.